Light sources for film and television lighting come in several different categories.
Open-face lamp assemblies are characterized by having light sources and reflectors. If a distance between such a light source and a reflector can be varied, the light therefrom can be focussed. Open-face lamp assemblies are not always really "open", often light outlet openings thereof are covered by light-transmissive shields. In some instances, light-diffusing foils are mounted at varying distances for increasing an illumination, radiation, or reflecting, angle and enlarging an illuminated area.
Directly-radiating open-face lamp assemblies usually do not produce good quality light. Blinds, or shutters, used with such lamp assemblies often cause double shadows, a focus area thereof is small and light quality thereof does not necessarily meet high standards. Directly lighting an object with open-face lamp assemblies creates hard shadows.
Indirectly-radiating open-face lamp assemblies, which include lighting pans, or bowls, have light sources which do not emit light directly towards objects. Light is emitted towards reflectors which, in turn, reflect it towards the objects. Thus, illuminated areas are enlarged and shadows become softer. Such lamp assemblies cannot be focussed.
A projecting lamp assembly normally comprises a light source and a reflector which can be moved together. A lens (almost always a step lens) is immovably mounted. Such lamp assemblies can be focussed. Their light is of better quality than that of open-face lamp assemblies. Blinds, gates, or shutters, do not cause double shadows typical for some open-face lamp assemblies.
All lamp assemblies which emit light directly (that is, without light diffusers) cast hard shadows; particularly in small rooms the use of several such lamp assemblies causes multiple shadows (the calling card of a bad cameraman).
An attempt to enlarge an illuminated, or reflecting, area by mounting diffusing material in a frame in front of such a lamp assembly results in loss of control by the lamp assembly itself of the illumination, or radiation, angle, because this is then determined by the diffusing materials. Thus, portions of the object are often lighted which actually should not be lighted. Therefore, black shutters are mounted on upper, left, right and bottom sides in front of such a diffuser frame for again limiting the radiation angles of the light. Such an arrangement (for a single light source) works only with a stand for the lamp assembly, another for the diffuser frame and four more for the black shutters, or blinds. This might possibly work in a studio, but at original film sites where, nowadays, many television series are filmed, this takes up a lot of space, is cumbersome and requires too much time. Therefore, it would be beneficial for many lighting arrangements if an illuminated area could be enlarged without enormous construction and multiple stands (thus saving space), while, at the same time, control of the illumination angle is maintained.
It is important to be able to control the illumination angle when working with "spotlights", that is, light that falls onto an object from the direction of the camera. Controlling the illumination angle is important, because in this manner one can prevent portions of the set which are not to be illuminated from this direction from being illuminated (thus allowing also for control of shadows). Even more important is the ability to control a light outlet when light is used behind an actor (as a highlight, such as side lighting coming from behind and the side). This direction of light is particularly important for a one-eyed film and television camera for "setting off.revreaction., or distinguishing, an actor from his background. When using such light sources, of course, no light should fall directly onto the camera, thus, limiting the outlet angle is particularly important. When using conventional lamp assemblies (open-face projecting lamp assemblies or step-lens projecting lamp assemblies) for this purpose, light outlets are easily controllable by blinds mounted on the lamp assembly, possibly also by viewing hoods. However, the reflecting area remains small and the shadows are hard.
Many television series today are filmed on site with main light sources of a room being used as well. These may be fluorescent tubes on office ceilings or large window areas. Particularly in such rooms, it is not desirable to use lamp assemblies with small illuminated areas, because with such lighting arrangements hard shadows appear to be unnatural. Nevertheless, the light must be structured, or controlled.
In the near future, light sources with fluorescent tubes will substantially gain in significance for such lighting arrangements.
To date, all light sources with fluorescent tubes have been large and cumbersome. In addition, their light intensities have not been high enough to allow for noticeable lighting effects at greater distances.
New technologies concerning fluorescent tubes, such as folded coupled tubes, now allow, in connection with high-frequency operation of these tubes, one to fabricate smaller lamp assemblies with fluorescent tubes and to increase their light output so as to cover greater distances.
At the same time, light sensitivity of video cameras and films has increased. All of these factors allow one to work with substantially less light than before. All of these factors favor the use of lamp assemblies with fluorescent tubes.
Since fluorescent tubes use substantially less energy than other light sources, sufficient lighting can be provided in rooms with regular power outlets without requiring special electrical provisions. In addition, light of fluorescent tubes is cooler (more lumen per Watt).
Lamp assemblies having fluorescent tubes cannot be focussed. In this regard, optical provisions cannot be used for directing their light, because light sources thereof are not pin-pointed. Reflectors can increase light efficiency, but they cannot have a significant effect because of the given, very wide illumination angles of these lamp assemblies. Grids are sometimes mounted at the fronts of these lamp assemblies to somewhat influence the direction of the light from their light sources. Many office lamp assemblies have such light grids. In offices working with monitor screens, the grids are mounted relatively low and slats of the grids are spaced closer together to decrease an illumination angle. Such a grid is mounted higher with slats thereof being spaced wider apart for enlarging the illumination, or reflecting, angle.
It is an object of this invention to provide a lighting assembly which allows alteration of an illumination angle in an uncomplicated manner, even when fluorescent tubes are used.